welcome to Café Ludwig

There are many nooks and crannies in this place, this corner is for chats and tips about cameras, computing, and sharing photos, aimed at folks fairly new to the hobby. From the “front door” you can get to other topic areas and especially the galleries. Do visit the other corner of Café Ludwig for more on photos and photography.

Relax and read about your favorite pastime, you do need to bring your own cup of coffee.

Right now a lot of sprucing up is going on. You may have noticed the updated layout and a more readable font. Other changes are coming, so please excuse the dust.

Museum Photography

Museums present a treasure trove of fascinating artifacts that can make appealing photographs. Museum photography offers a whole set of challenges that you need to tackle to bring home beguiling images of those tokens of days past. Here are my thoughts that might help you to make a museum visit a fun and productive experience.LJK11819-P3-1024

The first obstacles to museum photography are the rules imposed by the institution. Some museum strictly prohibit any photography, on the other end of the scale are places that urge you to bring your camera. Most are somewhere in between.

The larger museums may have extensive information about taking pictures on their website. They also tend to be the most restrictive. If you don’t find specific information on photography give the museum a call and ask.

The most likely rules let you take photographs for your own use – no publication, commercialization or selling of the photos. You can often get permission for such use, but generally that involves fees, special scheduling, supervision, and approval of the final images. That is beyond the scope of this article.

LJK11787-P4-1024Some museums restrict the type of cameras that can be used. Cellphone cameras and unobtrusive point-and-shoot cameras are more likely to be allowed. Anything that looks like professional gear may be frowned upon.

For security reasons museums, like so many other places, tend to prohibit backpacks and large cases. Plan on travelling light, just the camera and maybe an extra lens – not much more.

Expect that tripods are not allowed, they do impede traffic and the enjoyment of the exhibits by other visitors. Flash or other artificial light may generally not be used. Many artifacts have delicate paints and pigments that are affected by light and the use of bright lights will degrade these items, obviously something you don’t want to do.

Having maneuvered around access restrictions you are now faced with another set of obstacles.

Museums tend to be dark places. That means using large apertures, slow shutter speeds that you can successfully handhold, and high ISO, sensor sensitivity, settings. Not the best formula for crisp, sharp images. Be prepared to spend a good deal of time on post-processing.

Learn to handhold your camera for steady pictures. Lens vibration reduction features can help a great deal. Bracing your elbows against your body and holding your breath during the exposure can allow shutter speeds below 1/10 of a second.

LJK11824-P3-1024In many instances there will be light from windows or skylights in addition to localized spot lighting. Not the best formula for color photography. You will just have to make the best of it. The overhead spot lights may not provide the best lighting for photography, but there is little you can do. Find the best angle that will allow you to create a compelling image.

Especially smaller artifacts will likely be in glass cases. Museums generally try to keep these quite clean, but reflections can be a pain. The closer you come to the glass the easier it is to avoid reflections from room lights, yourself, your camera and things behind you. Do not touch your camera to the glass, that might interfere with your lens focusing and may introduce vibrations. Do not brace yourself with a hand against the glass, your fingerprints can only detract from the experience of the visitors behind you.

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For larger objects you have the added problem of disturbing other items or even visitors on the other side. The shallow depth of field at large aperture settings helps a great deal. You should also consider getting down on a knee to get an upward angle. The higher walls and ceilings may make for a more pleasing background. Of course, a downward angle might also be possible, but do not even think of climbing on displays or furniture.

Post-Processing

So you did the best you could and have a haul of exposures to process into your masterpieces.

Here is an example that I took all the way to “café art”. This photo is of a head of the Greek goddess Demeter at the Michael C. Carlos Museum, Emory University, Atlanta, Georgia. It was hand-held at 1/6 sec. The other parameters are f/5.6, 55mm, ISO 1600. There was just a tiny bit of camera shake visible at high magnification.

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My camera is not of the latest technology and high ISO settings show a great deal of noise. Your camera may do a lot better. On a visit to the above-mentioned Carlos museum I used mostly ISO 3200 – the highest setting – to allow shutter speeds of around 1/15 second. To reduce the noise in the photos I used the “edge-preserving smooth” tool in PaintShop Pro. Here is an illustration of the tool’s effect:

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The screenshot on the left shows the original, the one on the right the resulting smoothing. For this illustration I used a higher setting than I actually used in order for the effect to be more obvious in this blog post. A high smoothing setting results in a “painterly” look as you can see. It does, however, reduce the apparent noise enough so that further processing steps can bring out the best in the photo. For the illustrations above and the one below, all from the Carlos Museum, I mostly maintained the warm look of incandescent illumination since that is what the museum uses. Here is the head of the Aphrodite statue, one of the museum’s prize properties.

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Here the lighting in the museum and the background work well.

For some photos, where the lighting was too contrasty because of localized spotlights, I found using HDR effect tools useful for flattening the tones. My favorite one is the HDR effect in onOne Perfect Effects 8. A similar tool , but a bit harder to use, is also found in Picasa.

I used the HDR effect tool on the photo below to bring out the detail of the machinery. This photo is from the Southeastern Railway Museum, Duluth, Georgia. This museum is a delight for photographers – your cameras and even tripods are welcome. The photo below was a 20 second exposure taken inside one of their large buildings. Clearly not in reach of a handheld camera.

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Even the interiors of outdoor displays require long exposures. The above photo was a 3.6 second exposure.

For another outdoor photo the problem was a a gray, overcast sky. My solution for this was to make the photo into a line and ink “painting”.

General II

There is much to see at museums, and many photo opportunities. Enjoy!

….

Michael C. Carlos Museum, Emory University

Southeastern Railway Museum, Duluth, GA

A day at the Southeastern Railway Museum with the SPS

This article was simultaneously published on Photography Notes and Tips

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© 2014 Ludwig Keck

Lost your friends to the shadows?

So often I see photos that show people almost totally lost in shadows. Maybe a group standing in front of the Eiffel Tower – beautiful detail in the landscape, but the faces of the people are totally unrecognizable because of the shadows falling across their faces. LJK11511-P7

Especially in photos taken with on-camera flash, the folks in front are way overexposed and the ones in the back row lost in the dark. It need not be so, there is help my friends! Some times all it takes is to let Auto Correct in Photo Gallery or a small move of the Shadows slider over toward the right to set matters right. In PicasaI’m feeling lucky” may do the trick or the Fill Light slider.

The dark areas of our photos hide a lot of detail that is often totally unrecognizable. Those details can be brought out. It may not result in award-winning photos, but it may make all the difference at a family gathering.

The photo above won’t let you bring out any detail in the figure, so don’t bother to try. It is a “doctored” photo, I made the figure, actually a flat sculpture, totally black.

I did make some experiments to see just how much information can be extracted from a painfully underexposed photo. I used a white cloth with a near-white plate and a white egg on that. The lighting was very soft, diffused window light so there would be hardly any shadows. My camera decided that the exposure at f/11 should be 1/15 of a second. Now we all know that cameras can’t tell an all white subject from a normal scene. You have seen photos of those white dogs romping in snow – they are just a dingy gray all over. So I over-exposed by 2 1/3 stops – used a shutter speed of 1/3 second. Here is my photo as seen in Photo Gallery.

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Note the histogram chart on the right. It shows the relative number of pixels of each shade, from totally black on the left to totally white on the right. There are just a few pixels that are below the halfway mark on the chart. The most pixels are bunched up near the right, the white, end. The cloth is not completely white and you can make out some texture in it. But looking at the photo you would conclude that indeed I had used a white cloth, a white plate, and a white egg, and the photo fairly represents my subject.

The next photo here shows the same scene but photographed at 1/250 second – four stops under the camera selected exposure, 6 1/3 stops below the photo above.

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Hopeless, wouldn’t you say? Take a look at the histogram. All the pixels are bunched up tightly on the black end. But note that they are just a tiny bit above the left end. There must be some data there.

Photo Gallery offers a number of sliders in the Adjust exposure panel. Those little doohickeys under the histogram are sliders too. They can be used to tell Photo Gallery to spread out the data. By sliding down the one on the white end you can tell Photo Gallery which pixel value to amplify up all the way to the white end, the rest will be proportionally lightened too. Lets see what happens when the “white” histogram slider is moved way left to just above where there is pixel data.

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Look at the picture. Amazing, isn’t it? Not quite as white as it should be. So let’s use the Brightness slider to finish the job.

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Well, what do you think? Yes, it is astonishing how much useful picture information can hide in shadows. I hope I have convinced you that you should take another look at your “uselessly underexposed” photos. As I said, maybe not gallery quality, but certainly very much worth doing.

For a bit more background on the histogram, see my post in Photography Notes & Tips Use the histogram to improve your photos.

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© 2014 Ludwig Keck

Dust bunnies, dirty lenses and stuck pixels

Modern cameras are absolute marvels at what they can do and how well they do it. Even with much abuse they produce pictures that are almost flawless. There are limits and little problems that will reveal themselves on close examination. This article explores some of those.

Dust Bunnies – the bane of interchangeable lens cameras

If you can remove the lens from your camera, it is almost certain that a little bit of dust will sneak in before you can cap it or install another lens. Such a speck of dust can settle on the sides, the mirror in a DSLR, or on the image sensor. Well, not exactly the sensor, that has usually some optical items stacked on it. If a speck settles on the filter in front of the sensor it will imped the light falling on a small number of the imaging pixels. You can see such specks in photos as “dust bunnies”. Before I go on, let me show you an example, a fairly drastic one I might add:

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PNT1401-01-10686-02There are many “dust bunnies” in the photo above, some of them are indicated by arrows. Here is a close-up view of the one indicated with a yellow arrow (top center) in the photo. The close-up shows the speck as photographed at f/36 while the photo above was taken at f/20.

The smaller the aperture, larger the f-number, the more noticeable will be the dust on the sensor. In fact at wide apertures and even mid-range (f/8 to f/11) the beam of light reaching any pixel is wide enough that a little bit of dust wont show. So it is a problem only when shooting at small apertures, for example in landscape photography when you want everything sharp from the foreground to the far mountains, when you want a really wide depth of field and thus choose a small aperture like f/22.

So, what can be done?

Obviously you will want to keep your camera as clean as possible. Always point the camera opening down when removing the lens – better to let dirt fall out than in.

Your camera most likely has a couple of tools for fighting dust bunnies. Most cameras have a dust-off feature. A bit of ultrasonic vibration is applied to the filter to shake any dust loose and have it, hopefully, fall to the bottom. There might be a surface there designed to be sticky to dust so it gets trapped. The camera can usually be set to perform this function regularly when you turn it on or off. This is like a dog shaking itself dry, but not nearly as vigorous, and hence not nearly as effective.

The second tool in your camera admits that some dirt may remain firmly stuck to the sensor. It lets you take a “dust reference photo”. Nikon calls it “dust off ref photo”. Check you camera manual to see how to record such a frame. The idea is to use this reference photo and subtract the spots in processing in your computer. Again Nikon has such a tool built into its Capture NX software (extra cost item), other manufacturers provide similar tools.

You can clean your camera sensor. That is a very delicate operation. First you need a clean room to do this in, and appropriate tools. Just like having a scalpel does not make you a brain surgeon, having a sensor cleaning kit does not impart the proper skills for operating on your camera. This task is best left to professionals. Your friendly camera store likely offers this service along with other camera maintenance services. A cleaned camera sensor will stay clean until you remove the lens – which like would be the very next day. So I have this service performed only when I want something else done to the camera.

Lastly there is the practical approach. Accept the fact that the world is not perfect. Inspect your photos – especially those that you will proudly show off to friends and strangers – and use the retouch tool, or healing brush, in your post-processing software to edit out any spots.

Dirt on the lens

The front element of your camera lens is exposed to the environment and dirt, even fingerprints, can easily get on it. With interchangeable lenses the back element can LJK10588-P2-Balso pick up dirt. Is that a problem? Most of the time not at all. The little bit of light blocked by even a fairly sizable spot will not affect the photo. There are conditions, however, under which dirt on the lens will show in photos and be very bothersome. Let me show you such an example.

The photo here shows a candle with a number of very much out-of-focus lights in the background. Some of these light patches are very sharply defined and you can see spots in them. Those little black spots come from dirt on the lens. You would definitely notice dirt of that size by looking at your lens. I am confident that you would take your lens cleaning brush and dust it off.

So what is this rare circumstance when dirt will show and why does it not show for all the out-of-focus light patches in this photo?

Dirt on the lens will show when the bundle of light coming from the lens is intercepted so it will be imaged as a large circle and when that light comes from a very small source, In the case of the photo here, some of the lights were pin-point small lights – LEDs. The patches not showing the dirt were made by larger lights. Essentially point sources are required to show up this problem.

What can you do? Clean your lens. Be very careful doing that, your lens has thin layers of anti-reflection coatings. You do not want to scratch those.  Follow the instructions in your manual.

If you are bothered by the fact that some of the bokeh patches, that’s what they are called, are not round but rather boat-shaped, hold your question for a discussion of optics. We won’t get into that in this article.

Stuck pixels

Your camera sensor has millions of individual light sensors, “pixels”. As with all electronic devices some of those tiny sensors may go bad. Having a few non-functioning pixels is not a serious problem and you may not even notice them. A non-functioning pixel might be stuck off and not provide any signal. That would  result in a black spot. A black spot would go unnoticed in almost all photos.  It could also be stuck on and produce a full output signal. That would show as a tiny white spot. We are sensitive to spots of light and a stuck on pixel is much more noticeable.

 

PNT1401-01-8698-01Now just one pixel would seem that it should not be of any concern at all, but there is more to the story. In order to produce color photographs, the sensors in the camera are equipped with color filters. Really tiny filters, some pixels have green, others blue, and others red filters. The pixels with their various filters are arranged in patterns. Rather than provide images made up of red, green and blue little patches, cameras provide three color signals for every pixel. That increases the apparent resolution and goes back to the early days of digital cameras when sensors had only thousands of pixels rather than millions as they do today. To produce the color information for each pixel the computer in the camera looks at the signals from adjoining pixels and calculates what the missing two colors should be. Why this lecture on minutiae? Because a stuck pixel will not show up as a single pixel but rather a patch since it affects what is calculated for adjoining pixels.

The photo here shows an evening scene with the moon and a star. Well, that star, so nice and sharp in this picture, is a stuck pixel rearing its little head.

Let’s take a closer look at that “star”. PNT1401-01-8698-02

You can see that at least an area of nine pixels is affected. In the actual file data an even larger number can be identified as different from the surrounding area.

Stuck pixels are permanent defects that may be affected by various environmental conditions including sensor temperature. They will tend to be more noticeable in long exposure photos because for those the sensor is operating for a longer period of time and getting warmer is it does its job.

Here again a reference exposure can be used to eliminate the artifacts in post-processing. If you are into astronomical photography you will definitely want to do that.

For the rest of us a stuck pixel will go unnoticed in most photos. If it shows up in a contrasting area, it can be easily touched up in post-processing. There are not likely to be many of those in your camera.

Well, I hope you have gained some useful information from my story on dust bunnies, lens dirt, and stuck pixels. Now I have to go and see if I can get my dirtied-up camera clean again. Ah, the things we do for our readers!

[This article was first published in Photography Notes & Tips.]

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© 2014 Ludwig Keck

Composition Rules

My readers know that I am eager to try out new things. Sometimes I try to get the very newest tool or product, at other times I am willing to let a few other folks go first. You also know that I am eager to share what I have learned.

A service provided by HP, called MagCloud, offers fast, high quality publishing. Calendars, magazines, booklets and more, can be easily set up and published in ebook form and in nicely printed versions, all at fairly modest prices.

My first venture in trying out this service is a little booklet, just 24 pages, about composition rules for photographers. The link below gets you to my MagCloud page where you can purchase the booklet.

You can see all of what is in the pamphlet, and actually a little bit more, on another of my blogs. See Composition Rules at Photography Notes and Tips.

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© 2013 Ludwig Keck

The making of a Photo

When you are out and about enjoying the world you may come upon a site that appeals to you. You may want to share the feeling of joy and you take a picture. The camera does a fine job of recording what it sees. But the camera cannot capture the warmth of the sunlight, the chirping of the birds, the rustling of the breeze. It cannot add how you feel to your picture.

“Post-processing”, editing, enhancing, your photos can bring out the “essence” of what you tried to convey. Here in four steps the “creation” of a photo.

First the picture as it came from the camera.

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There are some reflections of man-made objects that detract from the photo. In the real world these were ignored when I saw the scene, but in the photo they are bothersome. The clone tool in PaintShop Pro is what I used to remove these flaws.

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I remembered the scene, and especially the soft evening sunlight, as much brighter. The next editing step was to bring out the light by increasing the contrast and color saturation. There are many tools for doing this. Most of the time the sliders in Photo Gallery get me just what I want. Sometimes I will use Picasa and play with the “Boost” tool as I did for this photo.

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Still not totally convinced that the resulting photo presents the mood of the scene I decided to add some vignetting, darkening the sides. This step I like to do in PaintShop Pro but occasionally I will try the “Lomo-ish” tool in Picasa. I did so for the final touch.

Last Evening Light

I hope you can now see and feel the scene almost like I remember it.

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© 2013 Ludwig Keck

A Fall View

Here is something that is hard to do in any other display media: A tall image that you have to scroll to see.

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This is actually a vertical panorama, stitched together from eight separate exposures. Photo Gallery doesn’t mind which way, or in what order you take a group of overlapping shots. It does a fine job of matching together your world.

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© 2013 Ludwig Keck